Conventional film cartridges, such as 35 mm film cartridges, have a film leader extending therefrom at the time of purchase, and a brush or similar mechanism at the cartridge""s film slot to prevent light from entering the cartridge and exposing film contained therein. Another type of film cassette is variously referred to as an xe2x80x9cAPS film cassettexe2x80x9d (wherein APS means Advanced Photo System), a xe2x80x9cfilm safe cassettexe2x80x9d, or a xe2x80x9cSSU film strip loaded cartridge.xe2x80x9d One example of such a film cassette is KODAK(copyright) brand ADVANTIX(copyright) film. The cameras with which these film cassettes are used are known as APS cameras. APS film cassettes do not, at the time of purchase, or at the time the film is first inserted into the camera, have a film leader extending from the cassette to facilitate film loading. Instead, APS film cassettes have a light lock door that must be opened in order to advance or scroll the film from the cassette. Once the light lock door of the film cassette has been opened, ambient light is free to enter the cassette and expose the film within the cassette. Therefore, the light lock door of an APS film cassette must be opened either inside of a light sealed camera or in darkroom conditions to prevent the film therein from being inadvertently exposed.
In conventional cameras, such as conventional 35 mm cameras, film is usually loaded from the back of the camera by opening a back door thereof, placing the cartridge into the camera, pulling the film leader across the camera, engaging the leader on a take-up spool and then closing the back door. Since opening the light lock door of an APS film cassette in the presence of light can expose the film within the cassette, conventional methods of loading film are not suited to APS cameras.
A typical APS film loading sequence involves loading film into the camera through a film cassette door disposed on the bottom of the camera and then closing the film cassette door to light-tightedly seal the camera. Following this, the light lock door of the film cassette is opened. The film is then driven out of the cassette, across a film path, and into a film spooling area on the opposite side of the camera from the cassette. Before the cassette can be removed from the camera, the film must be rewound back into the cassette, and the light lock door must be closed. Thus, APS cameras are designed to prevent opening of the film cassette door when the light lock door is open.
So called single use cameras are known in the art. A single use camera is one that has been preloaded with film at the factory and sold to the consumer with the intent of being used only a single time (i.e., with only the roll of preloaded film) by the end user. (Preloading generally connotes the process of loading the camera with a spool of unexposed film in a film spool compartment that is opposite the film cartridge/cassette compartment such that, as exposures are taken, the exposed film is wound back into the film cartridge or cassette. Prewinding connotes the process of winding or spooling the unexposed film into the film spool compartment.) For 35 mm single use cameras, this is usually done by loading the film into the back camera in much the same way that a conventional 35 mm camera is loaded, then securely assembling a back cover to the camera by a locking mechanism, screws, adhesives, thermal bonding, etc. The film can be prewound into the film spool compartment of the camera either before the back cover is affixed to the camera (by spooling the film externally of the camera then placing the spool film in the film spool compartment) or after the back cover has been affixed to the camera (by applying a winding tool to the film spool). Typically, a package (such as paper, cardboard, plastic and/or adhesive labels) is placed on or around the camera body. (Hereinafter, the term xe2x80x9cpackagexe2x80x9d as used in connection with this application is intended to refer to both cardboard, paper, plastic and other types of packaging that may at least partly surround the camera body, and adhesive labels that may be affixed to at least front and/or back covers of the camera.) Depending upon the nature of the package, the film may not be removed without destroying at least part of the package. Usually, the film cannot be removed without destroying or disassembling part of the camera body. Additionally, film cannot easily be reloaded into the camera by the end user, at least not without partial destruction or disassembly of the camera body and/or its packaging. As described in commonly assigned U.S. Pat. Nos. 5,689,733 and 5,832,311 (hereinafter xe2x80x9cthe 733 and 311 patentsxe2x80x9d), the entirety of each of which is incorporated herein by reference, single use 35 mm cameras are usually loaded with the back cover removed so that the film leader can be attached to a film spool and/or so that the film can be wound into the film spool compartment.
Single use APS cameras are also known in the art. It will be appreciated that loading an APS film cassette into a single use APS camera presents special problems. The light lock door cannot be opened in non-darkroom conditions without exposing the film in the cassette, and thus conventional techniques used to preload 35 mm single use cameras cannot be employed unless film loading and final camera assembly take place in darkroom conditions. Prior art methods of loading film into single use APS cameras include performing the following steps in darkroom conditions, with the back cover of the camera removed: opening the light lock door of the cassette by inserting a tool or fixture into the light lock door spindle of the film cassette to rotate the light lock door to the open position before the cassette is placed in the camera; inserting a tool or fixture into the film spool spindle of the film cassette to drive a leader portion of the film from the cassette by rotating the spool inside the cassette with the tool or fixture; placing the cassette in a film cassette compartment of the camera; winding unexposed film from the cassette into a spool in a film spool compartment of the camera; then, assembling the back cover to the camera. If the camera requires a battery, then depending on the construction of the camera, the battery may have to be loaded in darkroom conditions as well. Thus, loading film into a single use camera may be cumbersome, time consuming and labor intensive. An improved method of loading film and a battery into an APS single use camera in non-darkroom conditions is described in the 733 and 311 patents.
Single use APS cameras usually automatically close the light lock door on the film cassette after all of the film has been rewound back into the cassette. This is usually done by means of a film sensor or other mechanism. Therefore, one issue that must be addressed in designing an APS camera is that of closing the light lock door of the film cassette after all of the film has been rewound into the film cassette. (In reusable APS cameras, this issue also entails preventing opening of the film cassette door until the light lock door has been closed.) In order to determine when to close the light lock door, there must be provided some indication that the film has been rewound into the film cassette. Typically, an APS camera employs a film sensor for this purpose. The function of the film sensor is to sense the presence or absence of film in the film path disposed between the film cassette compartment and the film spool compartment. The film sensor typically extends into the film path and rests against the film when film is present in the film path, thus detecting the presence of film outside of the film cassette. When film is no longer present at the film path location where the sensor is disposed, the absence of film is detected and it is assumed that all film has been wound into the film cassette. This causes the light lock door to close either automatically or upon further rotation of the film advance wheel. See, for example, U.S. Pat. No. 5,600,395 and the 733 and 311 patents. Generally, the film sensor presses against the film when film is present in the film path and thus exerts a force on the film in a direction transverse to the direction of travel of the film. Moreover, this force exists at all times that the film is present, including when the film is in motion, and may cause the film to deflect transverse to its direction of travel. Observation has shown that the action of the film sensor pressing against the film while the film is wound into the film cassette (i.e., after an exposure has been taken) may cause damage to or deterioration of the film because the film might rub against an internal surface of the camera or because the action of the film sensor rubbing against the film may cause damage to or deterioration of the film.
It is therefore desirable to provide a single use APS camera that is simple to preload with film and which can be easily preloaded in non-darkroom conditions. It is also desirable to provide an APS camera wherein the film sensor is prevented from applying potentially damaging forces to the film. The present invention addresses these goals.
An APS camera has an aperture in its body that opens to the exterior of the camera and light tightedly provides access to a light lock door driver and a film sensor mounted within the camera. A preloading tool is used to manipulate, via the aperture, the light lock door driver so as to open the light lock door and to move the film sensor out of the film path. The preloading tool includes, at one end, a movable member for operating the light lock door driver and a fixed member for operating the film sensor. The other end is for manipulation by a user. The camera""s film advance mechanism is used to thrust film from the film cassette, into the film path, and into a film spool compartment after the light lock door has been opened and while the film sensor is held out of the film path. A winding tool is used to spool the film in the film spool compartment so as to pre-wind the film therein.
The light lock door driver is spring biased to urge the light lock door to a closed position, but is prevented from doing so due to interference from the film sensor when the film sensor is in a first position indicating that film is present in the film path. In addition, a brake is normally applied to the film sensor to prevent it from pressing against the film (and thus preventing it from sensing the presence or absence of film in the film path), except during a brief sensing interval that occurs during a short period of rotation of the film advance wheel. During the sensing interval, the brake is released and the film sensor is permitted to momentarily sense the presence or absence of film in the film path. If film is sensed, the brake is reapplied at the end of the sensing interval. If the absence of film is sensed, the film sensor moves to a second position (into the film path) wherein it no longer interferes with the light lock door driver, whereupon, due to the spring biasing, the light lock door driver rotates the light lock door to the closed position.
Other features of the invention are described below.